The Stovebolt Site Forums The Shop Area Driveline Install manual trans - stops 1/8" from bell housing

We are trying to install our rebuilt SM318 manual transmission onto our 1960 Chevy Apache, and the transmission stops about 1/8th of an inch from the bell housing.

We installed a new pilot bearing with a new clutch and pressure plate. The trans goes in about 1/4 of an inch before feeling a little resistance. We can swivel the trans back and forth and wiggle it to about 1/8th of an inch before it seems to not move closer.

A friend had the same issue with their 1982 Chevy truck and eventually took it to a transmission shop to get it installed. The shop claimed the pilot bearing was put in crookedly.

Has anyone else run into this problem?

The pilot bearing is about the only thing that can stop it where you at now. How hard are you pushing. I have been installing transmission for 70 years sometime they can be stubborn. Did you use a pilot shaft or alignment tool? I prefer an old pilot shaft over a plastic alignment tool.

Did you use guide pins in the top 2 holes in the bell housing when you installed it?

Even with a plastic alignment tool, it can be tough to get the shaft into the pilot bearing. I've pried on the clutch arm to release the clutch disc and it slips right in place. Definitely use guide pins on the top bell housing holes like Carl mentioned.
The only way the pilot bushing could be installed crooked is if the crankshaft is bored crooked, and that's not likely.

Thanks for the replies!


We did not remove the bell housing. The bell housing is attached to the engine and the frame, with the transmission hanging off the back of it. See the pic showing the trans before removal.


We did use the plastic alignment tool and can see how that might get you close, but not as close as if we used an original metal shaft. We are supposed to pick up all the spare transmission parts from the shop we use to rebuild ours. Maybe we can realign the clutch with the spare shaft, but I will try to pry the clutch arm first to see if that gets the transmission in.

The engine has never been rebuilt or changed, so I agree with you that the pilot bushing cannot be installed crooked like the transmission place told my friend.

Guide pins = two long bolts with the heads cut off and slots cut into them for a screwdriver to screw them into the back of the bell house to support the transmission. And yes a used shaft is better than the plastic alignment tool. Also, did you lube the pilot bushing and the front of the shaft before attempting to assemble? You could start your bolts and see if they will snug the transmission into place. Just some thoughts from my own experiences.

Did you compare the new pilot bushing to the old one removed to be sure they were the same thickness? A thicker bushing might prevent the input shaft from settling all the way in.

If they were the same thickness, perhaps the new pilot bushing didn't get fully seated in the crankshaft? That might keep the input shaft from sliding all the way in.

Alternative thought. Did you by chance replace the input shaft in the transmission? If yes, did you check the fit of the shaft with the new pilot bushing?

Just some random thoughts that might be related to your problem.

Yes, I put a little grease on the pilot bushing using the plastic input shaft. I wanted to leave the bolt idea as a last resort.


Yes, I compared the pilot bushing and also test-fitted it on the trans shaft. They reused my original input shaft, so that was good. I am not an expert on the internal parts, but was told the 1st and 2nd gears were bad along with the synchro's gaskets, etc.

So, I moved the clutch fork, as I used a pry bar against a crossmember on the back of the transmission, and it made that awesome sound as it fully contacted the bell housing. I guess I just needed a little extra push!! Hard to do by hand on the ground under the truck!

Thank you, everyone, for your help. The truck has been sitting in the backyard for over a year with no end in sight until one day I found someone selling an SM318 they had in the back of their storage trailer for years. Although the tail shaft was shorter (From a car with that X frame back in the day), the rest of the parts were in great shape, and he only wanted $20 for it. My transmission rebuilt below...

So glad to hear you won the battle!

How close to getting the truck back on the road???

Sounds like you put too much grease in the pilot hole.
It doesn’t take much grease to stop the pilot shaft from going in all the way.
Hydraulic pressure is what I use to remove the old bushing.

Don